scholarly journals Correction: Adaptation and Mal-Adaptation to Ambient Hypoxia; Andean, Ethiopian and Himalayan Patterns

PLoS ONE ◽  
2008 ◽  
Vol 3 (6) ◽  
Author(s):  
Guoqiang Xing ◽  
Clifford Qualls ◽  
Luis Huicho ◽  
Maria Rivera-Ch ◽  
Tsering Stobdan ◽  
...  
Keyword(s):  
Ambient Hypoxia

Hypoxia-induced changes in shivering and body temperature

1987 ◽  
Vol 62 (6) ◽  
pp. 2477-2484 ◽  
Author(s):  
H. Gautier ◽  
M. Bonora ◽  
S. A. Schultz ◽  
J. E. Remmers
Keyword(s):  
Central Nervous System ◽  
Body Temperature ◽  
Room Temperature ◽  
Co2 Concentration ◽  
Hypoxic Conditions ◽  
O2 Concentration ◽  
The Central Nervous System ◽  
Induced Changes ◽  
Maintain Body Temperature ◽  
Ambient Hypoxia

Experiments were carried out on conscious cats to evaluate the general characteristics and modes of action of hypoxia on thermoregulation during cold stress. Intact and carotid-denervated (CD) conscious cats were exposed to ambient hypoxia (low inspired O2 fraction) or CO hypoxia in prevailing laboratory (23–25 degrees C) or cold (5–8 degrees C) environments. In the cold, both groups promptly decreased shivering and body temperature when exposed to either type of hypoxia. Small increases in CO2 concentration reinstituted shivering in both groups. At the same inspired concentration of O2, CD animals decreased shivering and body temperature more than intact cats. While this difference resulted, in part, from a lower alveolar PO2 in CD cats, a difference between intact and CD cats was apparent when the two groups were compared at the same alveolar PO2. During more prolonged hypoxia (45 min), shivering returned but did not reach normoxic levels, and body temperature tended to stabilize at a hypothermic value. Exposure to various levels of hypoxia produced graded suppression of shivering, with the result that the change in body temperature varied directly with inspired O2 concentration. Hypoxia appears to act on the central nervous system to suppress shivering and sinus nerve afferents appear to counteract this direct effect of hypoxia. In intact cats, this counteraction appears to be sufficient to maintain body temperature under hypoxic conditions at room temperature but not in the cold.

Effects of hypoxia on metabolic rate of conscious adult cats during cold exposure

1989 ◽  
Vol 67 (1) ◽  
pp. 32-38 ◽  
Author(s):  
H. Gautier ◽  
M. Bonora ◽  
J. E. Remmers
Keyword(s):  
Oxygen Consumption ◽  
Metabolic Rate ◽  
Cold Exposure ◽  
Carotid Body ◽  
Cold Environment ◽  
Unit Change ◽  
Adult Cats ◽  
Carotid Body Chemoreceptors ◽  
Ambient Hypoxia

Oxygen consumption (VO2) and shivering movements were recorded in adult, conscious cats in a thermoneutral (24–27 degrees C) and in a cold (3–8 degrees C) environment during normoxia, hypoxia, or hyperoxia for 55 min. In the cold environment, VO2 correlated with shivering index (SI) under conditions of normoxia or ambient hypoxia (FIO2 = 0.12). During normoxia, VO2 was 63% higher in the cold than the thermoneutral environment. Ambient hypoxia acutely reduced VO2 in cold and thermoneutral environments, the decrement being greater for the former than the latter. Similarly, the variation in VO2 for unit change in SI was greater in hypoxia than normoxic conditions, suggesting that hypoxia influenced nonshivering as well as shivering components of cold-induced VO2. Hypoxia induced by CO (FICO = 0.002) also reduced VO2 and SI, a result that is consistent with previous results indicating that carotid body chemoreceptors do not mediate the suppression of shivering by ambient hypoxia. Hyperoxia increased VO2 and SI in the cold, and the effects of both hypoxia and hyperoxia in the cold were antagonized by increasing FICO2 to 0.03. The results demonstrate that hypoxia suppresses VO2 in the cold by reducing the intensity of shivering and, probably, by an action on metabolic rate that is unrelated to cold-induced calorigenesis.

Components of intestinal epithelial hypoxia activate the virulence circuitry of Pseudomonas

2005 ◽  
Vol 288 (5) ◽  
pp. G1048-G1054 ◽  
Author(s):  
Jonathan E. Kohler ◽  
Olga Zaborina ◽  
Licheng Wu ◽  
Yingmin Wang ◽  
Cindy Bethel ◽  
...  
Keyword(s):  
Fluorescent Protein ◽  
Surgical Stress ◽  
Recovery Period ◽  
Intestinal Lumen ◽  
Bacterial Cells ◽  
Intestinal Epithelial ◽  
Promoter Activation ◽  
Fusion Construct ◽  
Green Fluorescent ◽  
Ambient Hypoxia

We have previously shown that a lethal virulence trait in Pseudomonas aeruginosa, the PA-I lectin, is expressed by bacteria within the intestinal lumen of surgically stressed mice. The aim of this study was to determine whether intestinal epithelial hypoxia, a common response to surgical stress, could activate PA-I expression. A fusion construct was generated to express green fluorescent protein downstream of the PA-I gene, serving as a stable reporter strain for PA-I expression in P. aeruginosa. Polarized Caco-2 monolayers were exposed to ambient hypoxia (0.1–0.3% O2) for 1 h, with or without a recovery period of normoxia (21% O2) for 2 h, and then inoculated with P. aeruginosa containing the PA-I reporter construct. Hypoxic Caco-2 monolayers caused a significant increase in PA-I promoter activity relative to normoxic monolayers (165% at 1 h; P < 0.001). Similar activation of PA-I was also induced by cell-free apical, but not basal, media from hypoxic Caco-2 monolayers. PA-I promoter activation was preferentially enhanced in bacterial cells that physically interacted with hypoxic epithelia. We conclude that the virulence circuitry of P. aeruginosa is activated by both soluble and contact-mediated elements of the intestinal epithelium during hypoxia and normoxic recovery.

scholarly journals Altitude, Exercise, and Skeletal Muscle Angio-Adaptive Responses to Hypoxia: A Complex Story

2021 ◽  
Vol 12 ◽  
Author(s):  
Pierre Lemieux ◽  
Olivier Birot
Keyword(s):  
Skeletal Muscle ◽  
Cellular Level ◽  
Hypoxic Stress ◽  
Adaptive Responses ◽  
Skeletal Muscle Function ◽  
Pathological Conditions ◽  
Molecular Complexity ◽  
Exercise Induced ◽  
Ambient Hypoxia ◽  
Muscle Capillaries

Hypoxia, defined as a reduced oxygen availability, can be observed in many tissues in response to various physiological and pathological conditions. As a hallmark of the altitude environment, ambient hypoxia results from a drop in the oxygen pressure in the atmosphere with elevation. A hypoxic stress can also occur at the cellular level when the oxygen supply through the local microcirculation cannot match the cells’ metabolic needs. This has been suggested in contracting skeletal myofibers during physical exercise. Regardless of its origin, ambient or exercise-induced, muscle hypoxia triggers complex angio-adaptive responses in the skeletal muscle tissue. These can result in the expression of a plethora of angio-adaptive molecules, ultimately leading to the growth, stabilization, or regression of muscle capillaries. This remarkable plasticity of the capillary network is referred to as angio-adaptation. It can alter the capillary-to-myofiber interface, which represent an important determinant of skeletal muscle function. These angio-adaptive molecules can also be released in the circulation as myokines to act on distant tissues. This review addresses the respective and combined potency of ambient hypoxia and exercise to generate a cellular hypoxic stress in skeletal muscle. The major skeletal muscle angio-adaptive responses to hypoxia so far described in this context will be discussed, including existing controversies in the field. Finally, this review will highlight the molecular complexity of the skeletal muscle angio-adaptive response to hypoxia and identify current gaps of knowledges in this field of exercise and environmental physiology.

scholarly journals Ambient hypoxia enhances the muscle‐mass loss after extensive injury

2011 ◽  
Vol 25 (S1) ◽  
Author(s):  
Thomas CHAILLOU ◽  
Nathalie KOULMANN ◽  
Nadine SIMLER ◽  
Adélie MEUNIER ◽  
Corinne GREGOIRE ◽  
...  
Keyword(s):  
Mass Loss ◽  
Muscle Mass ◽  
Muscle Mass Loss ◽  
Ambient Hypoxia

scholarly journals Correction: Adaptation and Mal-Adaptation to Ambient Hypoxia; Andean, Ethiopian and Himalayan Patterns

PLoS ONE ◽  
2008 ◽  
Vol 3 (6) ◽  
Author(s):  
Guoqiang Xing ◽  
Clifford Qualls ◽  
Luis Huicho ◽  
Maria Rivera-Ch ◽  
Tsering Stobdan ◽  
...  
Keyword(s):  
Ambient Hypoxia

HIF-1α Negatively Regulates Irisin Expression Which Involves in Muscle Atrophy Induced by Hypoxia

2021 ◽  
Author(s):  
Shiqiang Liu ◽  
Pengyu Fu ◽  
Kaiting Ning ◽  
Rui Wang ◽  
Baoqiang Yang ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Muscle Atrophy ◽  
Skeletal Muscle Atrophy ◽  
Hypoxia Exposure ◽  
Chemical Hypoxia ◽  
Reduced Body ◽  
Background Exposure ◽  
Ambient Hypoxia ◽  
Hypoxia Treatment

Abstract Background: Exposure to high altitude environment leads to skeletal muscle atrophy. As a hormone secreted by skeletal muscles after exercise, irisin contributes to promoting muscle regeneration and ameliorating skeletal muscle atrophy, but its role in hypoxia-induced skeletal muscle atrophy is still unclear. Methods & Results: Our results showed that 4 w of hypoxia exposure significantly reduced body weight and gastrocnemius muscle mass of mice, as well as grip strength and the duration time of treadmill exercise. Hypoxia treatment increased HIF-1α expression and decreased both the circulation level of irisin and its precursor protein FNDC5 expression in skeletal muscle. In vitro, CoCl2-induced chemical hypoxia and 1% O2 ambient hypoxia both reduced FNDC5, along with the increase of HIF-1α. Moreover, the decline of area and diameter of myotubes caused by hypoxia were rescued by inhibiting HIF-1α via YC-1. and Conclusions: Collectively, our research indicated that FNDC5/irisin was negatively regulated by HIF-1α and could participate in the regulation of muscle atrophy caused by hypoxia.

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